I am looking to re build some retro wheels and trying to work out what spoke lengths I need, I have tried using a spoke calc and coming up with 300mm using a metal tape and eyeing it in, sounds about right but pretty hap hazard! wondering if there is anyone with better expertise that can help me for sizes.I am using maillard 700 small flange hubs with schurmann super 27 x 1 1/4. from screwdriver in nipple slot to opposite I believe is 620 mm

I am looking to re build some retro wheels and trying to work out what spoke lengths I need, I have tried using a spoke calc and coming up with 300mm using a metal tape and eyeing it in, sounds about right but pretty hap hazard! wondering if there is anyone with better expertise that can help me for sizes.I am using maillard 700 small flange hubs with schurmann super 27 x 1 1/4. from screwdriver in nipple slot to opposite I believe is 620 mm

thanks

So long as you are getting close with the rule you are using to measure the hubs sizes, you won't be far off using a spocalc. Hopefully I've managed to attach an image of what I use to measure the rim diameter (effective rim diameter - ERD). Is the 300mm just for the front wheel, as you will be expecting 2 different sizes for the rear wheel because of wheel dish.

very intuitive and accurate way of doing it thanks very much.as for the hub flange diameter am I correct in saying it is measured centre to centre of opposite holes in the same flange?and the centre hub to flange can be done by flange to flange /2? (no offset)

if the calculator states I need 300mm spokes would I get away with 298mm as this is the largest I can find? the rear hub flanges are slightly larger so yes I am expecting different spoke sizes, perhaps 298's or 296's will be the exact ones for the job.

Front hub are measured from flange to flange, and then divided by two yes, rear hub is measured from where the hub sits in the rear fork

the pic to the right, measure the whole hub, and divide in two, then measure from flange to center of the whole hub, the 37.75 and the 16.75 make sense? The way I measure the rim is: Take a measure of the rim from outside to outside, lets say it`s 602mm, then measure from bottom of screwdriver insert in nipple to top of rim, multiply by two, and subtract from the rim diameter (602) That´s your ERD (effective rim diameter) Hub diameter is measured from hole to hole, opposite from each other.

right I've been doing some measuring, hope it's accurate enough. hub nut to nut 122.5 mm,left flange to hub centre 42 mm, right 17mm. hole to opposite is 42mm and erd 620mm. that everything?what tolerance do I have with length as nipple is 12mm I believe?cheers

If spoke count is 36, and you want a 3 cross, spoke length, drive side is 299.3 so 300 or 298mm nondrive side is 301.7 or 302mm 620mm sounds rather big, are you sure you have the correct measurement? here is a guide:

Carefully measure the outside diameter of the rim, from outside edge to outside edge, being careful to measure exactly in the center across the rim. To be sure the rim is round, measure in at least two locations 90 degrees apart. If the two measurements are different, measure in a third location and average the three measurements.Next, drop a spoke nipple into any hole in the rim. Using the depth gauge of the measuring caliper, measure from the top edge of the rim to the base of the screwdriver slot of the nipple. This represents where the end of the spoke should be when the wheel is fully tensioned.Using the measurement obtained in step 2, multiply the result by 2 and subtract that number from the measurement obtained in step 1 (the outside rim measurement). The result will be the Effective Rim Diameter (ERD).

Your LBS should have them if they build wheels on a regular basis, or they can order you some. But since 27 1 1/4 is an older rim it might be hard. I just looked on Ebay, and found a couple of auctions.

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